Dynamic Frequency Selection of channel assignment for APs in high density areas

[gunnar_amundson]

We have Ruckus ZF7263's at our hotel. Our vendor installed the APs with the auto configuration for channel settings. After doing a wireless survey I noticed that there were several adjacent APs assigned to the same channel. It seems from this observation that the auto assignment of channels doesn't always do a good job of assigning the channels. Is there a reason why I would have 6 adjacent APs would be assigned to the same channel? It seems that Dynamic Frequency Selection isn't the ideal way to setup APs in high density locations. Is it your recommendation to manually configure the channels instead of relying on DFS?

[gunnar_amundson]

Thanks for your comment. Very helpful!

[john_d]

Using ChannelFly in run-stop mode is a decent middle ground too and worth thinking about as an alternative to high MTBC. If you have sensitive clients, high MTBC will just delay the inevitable complaints from clients about wifi bouncing or dropping out due to clients not keeping up with channel switching.

I have found that low MTBC combined with 120 minute run-stop is a good combo.

[gunnar_amundson]

From reading these comments it seems to me that the advantages of Channelfly would be:
1. simplicity of configuration
2. Dynamic channel assignment for when there is a change in the environment where a channel change would benefit to avoid interference
3. to select the best channel for better throughput

The reason I posted here was because I saw the results of Channelfly assignments on our APs were contrary to everything I read and learned about channel assignments causing interference between adjacent APs.

At out hotel, the biggest problem is with supporting hand held wireless devices that by default have poor receptivity and are prone to interference and poor performance. Signal strength is critical to the performance of these devices. To enhance the signal strength I am considering deploying more APs. In our 5 story 177 room hotel we currently have 22 ZF7363 APs. Our guests that use smart phones are having issues with getting their connections dropped and receiving poor bandwidth performance. Other devices like laptops are not having these problems. Throughput is important, but in our hotel, reliable connectivity and signal strength are more important.

It seems to me that by manually assigning the channels to avoid interference of the signals on overlapping channels would benefit these hand held devices better than automatically assigning the channels for better throughput. I'm also wondering how much throughput are we looking at? A significant amount or just a little better? And is that amount of throughput really benefiting the hand held devices with connectivity issues.

[john_d]

The general problem with handheld devices is that they are very sensitive to the signal being weak, mainly because the user's grip can attenuate signals, the user tends to move around a lot which makes bad roaming decisions really devastating, and they are generally 1 stream so they'll see 1/2 or 1/3 of peak throughput anyway.

You may find that having more AP's is helpful if signal strength is an issue, or SmartRoam if you observe smartphones are not connecting to the most nearby AP. IMO both of these will benefit you more than channel assignments.

Especially in an environment like a hotel, dynamic noise from your guests bringing in rogue devices can often make conventional channel selection guidelines suboptimal. You can see from support info what ChannelFly measures every channel's capacity to be. The difference sometimes is huge.

[gunnar_amundson]

I can see the advantage of using Channelfly, but what advantages or conditions are there for configuring the channels manually?

Here is a comment about the results of having common channel assignments on adjacent APs.

http://www.wireless-nets.com/resource...

"setting access points near each other to the same channel will degrade capacity, and performance will be significantly lower as traffic on the network increases. As a result, it’s best to assign non-overlapping channels to nearby access points."

When I set the channel assignment to auto I noticed several adjacent APs assigned to the same channel. If the above statement is true, how could the automatic assignments to the same channels result in better performance or connectivity? Wouldn't those 6 APs signals have an effect on each others signals as they would with any other AP?

I'm thinking that Channelfly may be useful under some, but not all environments. I think the same may be true for manual assignments too. Even though one channel setting may have little impact, I'm looking at all aspects of a wireless network. Number of APs, location/placement of APs, channel assignment, and any other configuration that will improve our guest network.

I get comments about slowness, disconnections, connectivity problems to name a few. My tests do not show these results, but I haven't yet tested during the peak hours between 10PM and midnight. I do my tests using multiple devices iPhone, iPad, laptops (OSX and Windows), I have done numerous speed tests, wireless survey, heat map, etc. So even though channel assignments seem less significant, I have to look at every aspect to narrow down these issues.